Dump buckets have long been used to transfer material such as scrap metal and the like from a collection point for the scrap metal to an unloading station where the contents are dumped. The bucket is normally formed from metal and has a bottom, side walls, rear wall and a front wall that is inclined so as to permit dumping, by sliding, of the contents from over the front wall by lifting the rear portion of the bucket. A bail is secured to the bucket by which the bucket may be lifted by a crane hook for transfer of the bucket from a scrap collection station to a dumping station. In automatic dump buckets, the bail is locked in a vertical position for movement of the bucket by a crane to prevent unintentional tipping of the dump bucket from a horizontal transfer position.
One example of an automatic safety dumping bucket is illustrated in U.S. Pat. No. 3,230,003, where trunions, rigidly mounted on the bucket side wall, are slidably and rotatably received within slots extending along the sides of a U-shaped bail, with the slots located at the ends of the bail so as to permit the bail to be rotated about and have limited radial movement relative to the trunions.
Another automatic dump bucket is described in U.S. Pat. No. 3,374,907, to James M. Phillips and Alfred D. Parke, Jr. where pivot pins are attached to the side of a bucket and to a bracket also attached to the side of the bucket and the lifting bail is connected to the bucket in a manner such that when the bucket is at rest, or parked on the ground, the bail will swing rearwardly in only a limited arc to an inclined position. While this type of automatic dump bucket has found extensive use, there are certain features lacking from such a construction. For example, with the pivot pins attached to the side walls of the bucket, such as by welding, a possibility exists of the pivot pins shearing from the side wall. Also, there are situations which arise where the inclined position of the bail at rest can cause difficulties, and it would be beneficial to have an option where a bail could be maintained in a vertical position at rest, when desired.